Abstract: A technique to detect and locate smudgy character strings in complex tabular coupon images is presented.In our research‚character strings in the irregular coupon images are computer-printed but of low contrast and could be shifted out of the table so that they are unable to be detected and located using conventional algorithms.Based on geometric information and string retrieval result extended maximum average correlation height （EMACH） correlation filter is applied as an adaptive shift locator to detect and locate expected character strings.The results demonstrate that the algorithm is of high accuracy and provides excellent input for OCR.